title: Cardiopulmonary interactions in healthy children and children after simple cardiac surgery: the effects of positive and negative pressure ventilation.
abstract: OBJECTIVE
  To investigate the effects of cuirass negative pressure ventilation on the cardiac output of a group of anaesthetised children after occlusion of an asymptomatic persistent arterial duct, and a group of paediatric patients in the early postoperative period following cardiopulmonary bypass.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  The paediatric intensive care unit and catheter laboratory of a tertiary care centre.
  
  
  METHODS
  16 mechanically ventilated children were studied: seven had undergone surgery for congenital heart disease, and nine cardiac catheterisation for transcatheter occlusion of an isolated asymptomatic persistent arterial duct.
  
  
  METHODS
  Cardiac output was measured using the direct Fick method during intermittent positive pressure ventilation and again after a short period of negative pressure ventilation. In five of the postoperative patients a third measurement was made following reinstitution of positive pressure ventilation.
  
  
  RESULTS
  Negative pressure ventilation was delivered without complication, with no significant change in systemic arterial oxygen and carbon dioxide tension. The mixed venous saturation increased from 74% to 75.8% in the healthy children, and from 58.9% to 62.3% in the postoperative group. Negative pressure ventilation increased the cardiac index from 4.0 to 4.5 l/min/m2 in the healthy children, and from 2.8 to 3.5 l/min/m2 in the surgical group. The increase was significantly higher in the postoperative patients (28.1%) than the healthy children (10.8%).
  
  
  CONCLUSIONS
  While offering similar ventilatory efficiency to positive pressure ventilation, cuirass negative pressure ventilation led to a modest improvement in the cardiac output of healthy children, and to a greater increase in postoperative patients. There are important cardiopulmonary interactions in normal children and in children after cardiopulmonary bypass, and by having beneficial effects on these interactions, negative pressure ventilation has haemodynamic advantages over conventional positive pressure ventilation.
authors.affiliation: Department of Paediatrics, Royal Brompton Hospital, London, UK.
authors.forename: L S
authors.initials: LS
authors.lastname: Shekerdemian
authors.forename: A
authors.initials: A
authors.lastname: Bush
authors.forename: C
authors.initials: C
authors.lastname: Lincoln
authors.forename: D F
authors.initials: DF
authors.lastname: Shore
authors.forename: A J
authors.initials: AJ
authors.lastname: Petros
authors.forename: A N
authors.initials: AN
authors.lastname: Redington
mesh_terms: D000293:Adolescent; D002302:Cardiac Output; D002315:Cardiopulmonary Bypass; D002648:Child; D002675:Child, Preschool; D004374:Ductus Arteriosus, Patent / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011175:Positive-Pressure Respiration; D011184:Postoperative Period; D011446:Prospective Studies; D012123:Pulmonary Ventilation; D015919:Ventilators, Negative-Pressure